From 36058ceb30d24e3792b546f7709dc62ac8f4a11c Mon Sep 17 00:00:00 2001
From: Christian Stewart <christian@paral.in>
Date: Sun, 18 Apr 2021 20:45:30 -0700
Subject: [PATCH] osfs: add js shim

Signed-off-by: Christian Stewart <christian@paral.in>
---
 osfs/os.go       |  2 ++
 osfs/os_js.go    | 23 +++++++++++++++++++++++
 osfs/os_posix.go |  2 +-
 3 files changed, 26 insertions(+), 1 deletion(-)
 create mode 100644 osfs/os_js.go

diff --git a/osfs/os.go b/osfs/os.go
index 880389f..bcb3c6f 100644
--- a/osfs/os.go
+++ b/osfs/os.go
@@ -1,3 +1,5 @@
+// +build !js
+
 // Package osfs provides a billy filesystem for the OS.
 package osfs // import "github.com/go-git/go-billy/v5/osfs"
 
diff --git a/osfs/os_js.go b/osfs/os_js.go
new file mode 100644
index 0000000..1044b71
--- /dev/null
+++ b/osfs/os_js.go
@@ -0,0 +1,23 @@
+package osfs
+
+import (
+	"github.com/go-git/go-billy/v5"
+	"github.com/go-git/go-billy/v5/helper/chroot"
+	"github.com/go-git/go-billy/v5/memfs"
+)
+
+// globalMemFs is the global memory fs
+var globalMemFs = memfs.New()
+
+const (
+	defaultDirectoryMode = 0755
+	defaultCreateMode    = 0666
+)
+
+// OS is a filesystem shim for js.
+type OS struct{}
+
+// New returns a new OS filesystem.
+func New(baseDir string) billy.Filesystem {
+	return chroot.New(globalMemFs, baseDir)
+}
diff --git a/osfs/os_posix.go b/osfs/os_posix.go
index 7645dd5..c74d60e 100644
--- a/osfs/os_posix.go
+++ b/osfs/os_posix.go
@@ -1,4 +1,4 @@
-// +build !plan9,!windows
+// +build !plan9,!windows,!js
 
 package osfs